[Qemu-devel] [PATCHv2] fix linuxboot.bin and multiboot.bin to not hijack int19

[Gleb Natapov]

Currently linuxboot.bin and multiboot.bin option roms override int19
vector to intercept boot process. No sane option rom should do that.
Provide bev entry instead that will be called by BIOS if option rom
is selected for booting.

Signed-off-by: Gleb Natapov <address@hidden>
---

Note that this patch should be applied after qemu will upgrade to Seabios
that supports boot order. Otherwise there will be change in behavior
since option rom will not be selected for booting by default.

v1->v2:
 - change PRODUCT to BOOT_ROM_PRODUCT
 - move pnp header from OPTION_ROM_START to BOOT_ROM_START

diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
index c109363..748c831 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -22,6 +22,8 @@
 
 #include "optionrom.h"
 
+#define BOOT_ROM_PRODUCT "Linux loader"
+
 BOOT_ROM_START
 
 run_linuxboot:
diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S
index 9131837..cc5ca1b 100644
--- a/pc-bios/optionrom/multiboot.S
+++ b/pc-bios/optionrom/multiboot.S
@@ -20,6 +20,8 @@
 
 #include "optionrom.h"
 
+#define BOOT_ROM_PRODUCT "multiboot loader"
+
 #define MULTIBOOT_MAGIC                0x2badb002
 
 #define GS_PROT_JUMP           0
diff --git a/pc-bios/optionrom/optionrom.h b/pc-bios/optionrom/optionrom.h
index fbdd48a..aa783de 100644
--- a/pc-bios/optionrom/optionrom.h
+++ b/pc-bios/optionrom/optionrom.h
@@ -97,22 +97,28 @@
 
 #define BOOT_ROM_START                                 \
        OPTION_ROM_START                                \
-       push            %eax;                           \
-       push            %ds;                            \
-                                                       \
-       /* setup ds so we can access the IVT */         \
-       xor             %ax, %ax;                       \
-       mov             %ax, %ds;                       \
-                                                       \
-       /* install our int 19 handler */                \
-       movw            $int19_handler, (0x19*4);       \
-       mov             %cs, (0x19*4+2);                \
-                                                       \
-       pop             %ds;                            \
-       pop             %eax;                           \
        lret;                                           \
-                                                       \
-    int19_handler:;                                    \
+       .org            0x18;                           \
+       .short          0;                              \
+       .short          _pnph;                          \
+    _pnph:                                             \
+       .ascii          "$PnP";                         \
+       .byte           0x01;                           \
+       .byte           ( _pnph_len / 16 );             \
+       .short          0x0000;                         \
+       .byte           0x00;                           \
+       .byte           0x00;                           \
+       .long           0x00000000;                     \
+       .short          _manufacturer;                  \
+       .short          _product;                       \
+       .long           0x00000000;                     \
+       .short          0x0000;                         \
+       .short          0x0000;                         \
+       .short          _bev;                           \
+       .short          0x0000;                         \
+       .short          0x0000;                         \
+       .equ            _pnph_len, . - _pnph;           \
+    _bev:;                                             \
        /* DS = CS */                                   \
        movw            %cs, %ax;                       \
        movw            %ax, %ds;
@@ -122,5 +128,9 @@
     _end:
 
 #define BOOT_ROM_END                                   \
+    _manufacturer:;                                    \
+       .asciz "QEMU";                                  \
+    _product:;                                         \
+       .asciz BOOT_ROM_PRODUCT;                        \
        OPTION_ROM_END
 
--
                        Gleb.